# Software For Calculating "accelerated" Mortgage Payment

Q: Does anyone know of software that can calculate "accelerated" mortgage payment? "Accelerated" means paying an additional amount towards the principle each month. What I want to know is how much additional payment I have to make in order to shorten the life of my mortgage loan by X number of years. Any comments???

A: The expression to calculate loan/mortgage payments is: Payment = P*r/(1-(1+r)^(-n)) where: P = Principle amount (amount borrowed) r = rate of interest n = number of payments For example, if \$125,000 is borrowed at 8% annual interest for 30 years and payed off monthly, then: Monthly payment = \$125,000*(.08/12)/(1-(1+.08/12)^(-30*12) = \$917.21 (Of this \$917.21, the interest part is .08/12 times the present unpaid balance (which decreases every month), and the rest is principle paid. On the first payment, interest is \$833.33.) To find how much more you'd have to pay per month to shorten the life of your mortgage by X years, calculate the payment for Y years, then calculate it again for (Y-X) years. Spreadsheet programs (Quattro Pro, Lotus 123, etc) have an @function to perform payment calculations. Try ( for the above example): .

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